nicolas-brousse/_readme.md

## _readme.md

      
    Raw
  

              _readme.md
            
          
    Usage

@title = "Example title"

v = View.new("./view.erb", layout: "./layout.erb")
puts v.render(binding)
Stack Overflow

Question asked here: http://stackoverflow.com/questions/39059616/ruby-erb-create-a-content-for-method.

  
## layout.erb
<!DOCTYPE html>
<html>
<head>
  <title>
    <%= yield_content :title, "Default" %>
  </title>
</head>
<body>
  <h1>
    <% if content_for? :title %>
      <%= yield_content :title %>
    <% end %>
  </h1>


  <%= yield %>
</body>
</html>

## view.erb
<% content_for :title do %>
  <%= @title %>
<% end %>

<p>Page Example</p>

## view.rb
require "erb"

class View
  def initialize(template, layout: nil)
    @template  = template
    @layout    = layout
  end

  def render(variables = {})
    unless @template.nil?
      templates = [read_template(@template)]
      templates << read_template(@layout) unless @layout.nil?

      content = templates.inject(nil) do |prev, temp|
        _render(temp, variables) { prev }
      end
    end
  end

  def context
    @context ||= Context.new
  end

  def format_variables(v)
    case v
    when Binding
      h = {}
      v.eval("instance_variables").each do |k|
        h[k.to_s.sub(/^@/, '')] = v.eval("instance_variable_get(:#{k})")
      end
      h
    when Hash
      v
    else
      {}
    end
  end

  private

  def read_template(template)
    unless template.empty?
      path = ::File.expand_path("../#{template}", __FILE__)
      return ::File.read(path) if ::File.exist?(path)
    end
    template
  end

  def options
    @options ||= {
      :safe_level => nil,
      :trim_mode  => '<>-',
      :eoutvar    => '@_erbout',
    }
  end

  def _render(str, variables = {})
    opts = options

    format_variables(variables).each do |name, value|
      context.instance_variable_set("@#{name}", value)
    end

    context.instance_eval do
      # str = "<% @#{opts[:eoutvar]} = #{opts[:eoutvar]} %>\n" + str
      erb = ::ERB.new(str, *opts.values_at(:safe_level, :trim_mode, :eoutvar))
      erb.result(binding).sub(/\A\n/, '')
    end
  end

  protected

  # CommonHelpers.
  module CommonHelpers
    def content_for(key, content = nil, &block)
      block ||= proc { |*| content }
      content_blocks[key.to_sym] << capture_later(&block)
    end

    def content_for?(key)
      content_blocks[key.to_sym].any?
    end

    def yield_content(key, default = nil)
      return default if content_blocks[key.to_sym].empty?
      content_blocks[key.to_sym].map { |b| capture(&b) }.join
    end

    #
    def partial(path, variables: nil)
      return "" if path.nil?

      variables ||= binding if variables.nil?

      View.new(path).render(variables)
    end

    #
    def h(obj)
      case obj
      when String
        ::ERB::Util.html_escape(obj)
      else
        ::ERB::Util.html_escape(obj.inspect)
      end
    end

    private

    def capture(&block)
      @capture = nil
      @_erbout, _buf_was = '', @_erbout
      result = yield
      @_erbout = _buf_was
      result.strip.empty? && @capture ? @capture : result
    end

    private

    def capture_later(&block)
      proc { |*| @capture = capture(&block) }
    end

    def content_blocks
      @content_blocks ||= Hash.new {|h,k| h[k] = [] }
    end
  end

  class Context
    include CommonHelpers
  end
end
	<!DOCTYPE html>
	<html>
	<head>
	<title>
	<%= yield_content :title, "Default" %>
	</title>
	</head>
	<body>
	<h1>
	<% if content_for? :title %>
	<%= yield_content :title %>
	<% end %>
	</h1>


	<%= yield %>
	</body>
	</html>
	<% content_for :title do %>
	<%= @title %>
	<% end %>

	<p>Page Example</p>
	require "erb"

	class View
	def initialize(template, layout: nil)
	@template = template
	@layout = layout
	end

	def render(variables = {})
	unless @template.nil?
	templates = [read_template(@template)]
	templates << read_template(@layout) unless @layout.nil?

	content = templates.inject(nil) do \|prev, temp\|
	_render(temp, variables) { prev }
	end
	end
	end

	def context
	@context \|\|= Context.new
	end

	def format_variables(v)
	case v
	when Binding
	h = {}
	v.eval("instance_variables").each do \|k\|
	h[k.to_s.sub(/^@/, '')] = v.eval("instance_variable_get(:#{k})")
	end
	h
	when Hash
	v
	else
	{}
	end
	end

	private

	def read_template(template)
	unless template.empty?
	path = ::File.expand_path("../#{template}", __FILE__)
	return ::File.read(path) if ::File.exist?(path)
	end
	template
	end

	def options
	@options \|\|= {
	:safe_level => nil,
	:trim_mode => '<>-',
	:eoutvar => '@_erbout',
	}
	end

	def _render(str, variables = {})
	opts = options

	format_variables(variables).each do \|name, value\|
	context.instance_variable_set("@#{name}", value)
	end

	context.instance_eval do
	# str = "<% @#{opts[:eoutvar]} = #{opts[:eoutvar]} %>\n" + str
	erb = ::ERB.new(str, *opts.values_at(:safe_level, :trim_mode, :eoutvar))
	erb.result(binding).sub(/\A\n/, '')
	end
	end

	protected

	# CommonHelpers.
	module CommonHelpers
	def content_for(key, content = nil, &block)
	block \|\|= proc { \|*\| content }
	content_blocks[key.to_sym] << capture_later(&block)
	end

	def content_for?(key)
	content_blocks[key.to_sym].any?
	end

	def yield_content(key, default = nil)
	return default if content_blocks[key.to_sym].empty?
	content_blocks[key.to_sym].map { \|b\| capture(&b) }.join
	end

	#
	def partial(path, variables: nil)
	return "" if path.nil?

	variables \|\|= binding if variables.nil?

	View.new(path).render(variables)
	end

	#
	def h(obj)
	case obj
	when String
	::ERB::Util.html_escape(obj)
	else
	::ERB::Util.html_escape(obj.inspect)
	end
	end

	private

	def capture(&block)
	@capture = nil
	@_erbout, _buf_was = '', @_erbout
	result = yield
	@_erbout = _buf_was
	result.strip.empty? && @capture ? @capture : result
	end

	private

	def capture_later(&block)
	proc { \|*\| @capture = capture(&block) }
	end

	def content_blocks
	@content_blocks \|\|= Hash.new {\|h,k\| h[k] = [] }
	end
	end

	class Context
	include CommonHelpers
	end
	end